Behaviour 2019
Foraging preferences of two solitary, cavity-nesting bees managed as commercial pollinators.
Theresa Pitts-Singer1, Natalie Boyle2, Lindsie McCabe1. 1USDA ARS, Logan, Utah, United States; 2Pennsylvania State University, University Park, Pennsylvania, United States

The blue orchard bee (BOB), Osmia lignaria, is managed for U.S. orchard pollination, as it prefers rosaceous flowers. The alfalfa leafcutting bee (ALCB), Megachile rotundata, has an affinity for alfalfa flowers that has rendered it the primary managed pollinator for seed production in North America. However, the use of non-crop forage by these bees can help to sustain populations when crop flowers are unavailable or may reveal other plants for which the managed pollinators can be employed. Two studies recently addressed bee use of non-crop flowers for amassing brood provisions. In two studies each for BOBs and ALCBs, we monitored nest production and examined pollen in provisions. Both species collected pollen from crop plants of their preferred families when it was available but also collected from non-crop flowers. Generally, we found that BOBs switch to non-rosaceous plants after orchard bloom ends but are constant foragers on the crop flowers while they are present. When foraging in heterogeneous landscapes, ALCBs have a strong preference for alfalfa when present, will collect pollen from other legumes in the vicinity of alfalfa, and rarely use non-legume flowers.